1. Field of the Invention
The present invention relates to a driving device using an electromechanical transducer. Further, the present invention relates to an optical device for driving an optical component (a lens or the like) using the driving device.
2. Description of the Related Art
As described in JP-A No. 2001-60113, there have been well known driving devices of device-fixing types and free-running types, as driving devices utilizing electromechanical transducers. As illustrated in FIG. 1, a conventional device-fixing type driving device 21 is constituted by an electromechanical transducer (piezoelectric device) 23 secured to a stationary body 22 at its one end, a driving frictional member 24 secured to the other end of the electromechanical transducer 23 to move forwardly and backwardly in the longitudinal direction through the expansion and contraction of the electromechanical transducer 23 and a moving body 25 which frictionally engages with the driving frictional member 24. The driving device 21 causes the electromechanical transducer 23 to expand and contract at different speeds such that the driving frictional member 24 is slowly moved in a single direction to move the moving body 25 together with the driving frictional member 24 through the frictional engagement therebetween while the driving frictional member 24 is rapidly moved in the opposite direction to slide the moving body 25 with respect to the driving frictional member 24 through the inertia of the moving body 25. The conventional device-fixing type driving device 21 repeatedly performs the operation to continuously move the moving body 25 within the range of the length of the driving frictional member 24.
Further, U.S. Pat. No. 6,384,493 discloses a free-running type driving device having a basic configuration similar to that described in JP-A No. 2001-60113. As illustrated in FIG. 2, a conventional free-running type driving device 31 is constituted by a stationary member 32, a driving frictional member 33 which frictionally engages with the stationary member 32, an electromechanical transducer 34 secured to one end of the driving frictional member 33 and a moving body 35 secured to the other end of the electromechanical transducer 34. The driving device 31 causes the electromechanical transducer 34 to slowly expand and contract so as to maintain the frictional engagement between the driving frictional member 33 and the stationary member 32 for moving the moving body 35. Also, the driving device 31 causes the electromechanical transducer 34 to rapidly contract and expand to slide the driving frictional member 33 with respect to the stationary member 32 through the inertia of the moving body 35. The conventional free-running type driving device 31 repeatedly performs the operation to continuously move the moving body 35 within the range of the length of the stationary body.
In recent years, in order to drive optical components and the like of optical devices which have been advanced in miniaturization, there have been needs for small-sized driving devices with reduced overall lengths. However, with the conventional device-fixing type driving device 21, the moving body 25 is moved within the range of the length of the driving frictional member 24 by frictionally engaging the moving body 25 with the driving frictional member 24, which requires the driving frictional member 24 to have a length corresponding to the overall length of the moving body 25 plus the stroke of the moving body 25. In addition, in order to enable smoothly moving the long-and-thin driving frictional member 24 forwardly and backwardly in the longitudinal direction, the driving frictional member 24 is also required to have a length for providing bearings 26 and 27. Further, since the electromechanical transducer 23 is secured to one end of the driving frictional member 24, the conventional device-fixing type driving device 21 has the problem that the overall length thereof is greater in comparison with the stroke of the moving body 15.
Also, with the conventional free-running type driving device 31, the electromechanical transducer 34 is moved together with the moving body 35, which requires flexible wiring for supplying a driving voltage to the electromechanical transducer 34. In the case of realizing a significantly-small-sized free-running driving device 31, if the wiring is provided using a common flexible substrate, this can not provide sufficient flexibility, which hinders the movement of the moving body 35, thus inducing the problem of impossibility of stable driving.
FIG. 3 simply illustrates the configuration of the device-fixing type driving device 21 of FIG. 1. In the driving device 21, the driving frictional member 24 is secured to the electromechanical transducer 23 and the electromechanical transducer 23 is secured to the stationary body 22 using adhesives 28 and 29, respectively. In fabrication processes for the miniaturized driving device 21, it is difficult in practical to accurately apply necessary minimum amounts of adhesives 28 and 29 so as to spread them only within the bonding surfaces between the driving frictional surface 24 and the electromechanical transducer 23 and between the electromechanical transducer 23 and the stationary body 22. As illustrated in the figure, it is unavoidable that the adhesives 28 and 29 squeezed out from the bonding surfaces form protrusions on the side surfaces of the driving frictional member 24 and the electromechanical transducer 23. Consequently, the conventional device-fixing type driving device 21 causes the problem that the driving frictional member 24 should have a further greater length by an expected amount of protrusion a of the adhesive 29.